A population-based study on serious inpatient bacterial infections in patients with chronic lymphocytic leukemia and their impact on survival

Objective Infections in chronic lymphocytic leukemia (CLL) have been thoroughly investigated in the setting of clinical trials and single-center studies. However, large cohort studies on real-world data and studies on temporal trends are lacking. We performed a nationwide study on serious bacterial infections in CLL. Methods Using high-quality Swedish government-based registries, 13 009 CLL patients diagnosed in 1982-2013 and their 49 380 matched controls were included. Results Overall, CLL patients had an increased risk of serious inpatient bacterial infections with a hazard ratio (HR) 5.32 and 95% confidence interval (95% CI) 5.11-5.53, and the highest risk was observed for septicemia (HR 6.91, 95% CI 6.46-7.39) and lung infections (5.91, 5.64-6.18). The risk of serious inpatient bacterial infections decreased overtime with HR 0.87 (0.81-0.94) and HR 0.76 (0.70-0.82) in 1993-2002 and 2003-2013, respectively, compared to 1982-1992. CLL patients had an increased risk of death following a serious inpatient bacterial infection compared to matched CLL patients, and the risk was highest in the first 12 months after the infection (HR 5.48, 95% CI 5.11-5.90). Conclusion We have, in this nationwide study, characterized the risk of serious bacterial infections in CLL patients and, importantly, depicted that the risk has decreased overtime.